The present invention relates to energy absorbers, such as are used for absorbing energy in passenger vehicles. However, the present disclosure is not believed to be limited to only passenger vehicles.
Many different geometrically shaped thermoformed energy absorbers are known, such as those shown and described in U.S. Pat. Nos. 6,017,084; 6,221,292; 6199,942; 6,247,745; 6,679,967; 6,682,128; 6,752,450; 7,360,822; 7,377,577; 7,384,095; 7,404,593; 7,625,024; 7,628,444; and 7,625,036. These shapes have proven to provide dynamic force versus deflection curves that produce a relatively “square wave” shape when comparing their force properties as a function of deflection. Often, these formed energy absorbers lie between a Class-A surface (such as a bumper fascia, a headliner, or a door trim panel) and a rigid sheet metal structure in automotive applications. The energy absorber is typically designed with a 3-5 mm gap to one surface and attached to another. However, in some instances it becomes necessary to increase the overall depth of the energy absorber such that the unattached surface is closer to the other surface during normal vehicle operation. Further, product variation may cause some areas to become closer than the optimal gap distance. When the energy absorber lightly contacts the opposing surface, such as due to movement and inertia of the vehicle and relative components of the vehicle, a buzz, rattle, or squeak can be heard, which customers object to or find annoying. This noise occurs because the flat hard plastic surface can tap or slide against the opposing structure.
Materials are sometimes added to or placed adjacent energy absorbers in an effort to solve this problem. For example, in the past, a fabric pad, flock material, foam padding, or other kinds of flexible material have been added to one of the surfaces responsible for making the noise in an effort to lessen or eliminate the severity of the buzzing or tapping, and/or to eliminate the possibility of one surface translating into the other (or translating across the other causing a squeak). However, this requires the purchase and assembly of a separate component, causing added complexity, cost, and mass.